Igama lemveliso:i-polyurethane

Ulwakhiwo lwemolekyuli yemveliso:

Iinkcazelo ngeMichiza:

I-polyurethanes yaveliswa okokuqala kwaye yaphandwa nguDkt. Otto Bayer ngo-1937. I-polyurethane yipolymer apho iyunithi ephindaphindiweyo iqulethe i-urethane moiety.IiUrethanes ziphuma kwi-carbamic acids ekhoyo kuphela ngohlobo lwee-esters zazo[15].Inzuzo enkulu ye-PU kukuba ikhonkco aliqulunqwanga kuphela iiathom zekhabhoni kodwa kune-heteroatoms, i-oksijini, i-carbon kunye ne-nitrogen[4].Kwizicelo zamashishini, i-polyhydroxyl ikhompawundi ingasetyenziswa.Ngokufanayo, iikhompawundi zenitrogen ezisebenza ngemininzi zinokusetyenziswa kumakhonkco e-amide.Ngokutshintsha kunye nokutshintsha i-polyhydroxyl kunye ne-polyfunctional nitrogen compounds, ii-PU ezahlukeneyo zingenziwa [15].I-polyester okanye i-polyether resins equkethe amaqela e-hydroxyl isetyenziselwa ukuvelisa i-polyesteror polyether-PU, ngokulandelelana [6].Iiyantlukwano kwinani lokutshintshwa kunye nesithuba phakathi nangaphakathi kwamakhonkco esebe livelisa i-PUs ukusuka kumgca ukuya kwi-branched kunye ne-9 exekekileyo ukuya eqinile.Umgca wePUs usetyenziselwa ukwenziwa kweentsinga kunye nokubumba[6].Ii-PU eziguquguqukayo zisetyenziselwa ukuveliswa kwee-agent ezibophelelayo kunye neengubo[5].Iiplastiki ezinogwebu ezithambileyo neziqinileyo, ezenza uninzi lweePU eziveliswayo, zinokufumaneka ngeendlela ezahlukeneyo kwishishini[7].Ukusebenzisa i-prepolymers ye-molecular mass ephantsi, ii-copolymers zebhloko ezahlukeneyo zinokuveliswa.Iqela le-terminal hydroxyl livumela iibhloko ezitshintshanayo, ezibizwa ngokuba ngamacandelo, ukuba zifakwe kwikhonkco le-PU.Ukwahlukahlukana kula macandelo kubangela amanqanaba ahlukeneyo okuqina kunye nokuqina.Iibhloko ezibonelela ngesigaba sekristale esomeleleyo kwaye equlathe i-extender chain zibhekiswa kuzo njengamacandelo anzima[7].Abo bavelisa isigaba serabha ye-amorphous kunye ne-polyester / i-polyether ibizwa ngokuba ngamacandelo athambileyo.Ngokwentengiso, ezi polima zebhloko zaziwa njenge-Segmented Pus

Isicelo:

I-polyurethanes yenye yezona zinto zisebenza kakhulu kwihlabathi namhlanje.Ukusetyenziswa kwabo okuninzi ukusuka kwi-foam eguquguqukayo kwifanitshala ephakanyisiweyo, ukuya kwi-foam eqinile njengokugquma ezindongeni, uphahla kunye nezixhobo zombane kwi-thermoplastic polyurethane esetyenziswa kwizixhobo zonyango kunye nezihlangu, ukuya kwiingubo, izinto zokuncamathelisa, i-sealants kunye ne-elastomers ezisetyenziswa kumgangatho kunye nengaphakathi lemoto[17,18] ].Iipolyurethanes ziye zasetyenziswa kakhulu kwiminyaka engamashumi amathathu edlulileyo kwizicelo ezahlukeneyo ngenxa yentuthuzelo yazo, izibonelelo zeendleko, ukonga amandla kunye nokuvakala kwendalo esingqongileyo.Zeziphi ezinye zezinto ezenza ukuba i-polyurethanes inqweneleke kangaka?Ukuqina kwePolyurethane kunegalelo elikhulu kubomi obude beemveliso ezininzi.Izandiso zomjikelo wobomi bemveliso kunye nokugcinwa kobutyebi yingqwalasela ebalulekileyo yokusingqongileyo edla ngokukhetha ukukhethwa kweepolyurethanes[19-21].I-Polyurethanes (i-PUs) imele iklasi ebalulekileyo ye-thermoplastic kunye ne-thermoset polymers njengoko i-mechanical yabo, i-thermal, kunye neempawu zeekhemikhali zinokuthi zilungelelaniswe ngokuphendula kwee-polyols ezahlukeneyo kunye ne-poly-isocyanates.